CN115699910A - Communication device and communication method for multilink traffic indication map - Google Patents

Abstract

The present disclosure provides a communication apparatus and method for a multilink traffic indication map, the communication apparatus being an Access Point (AP) of a plurality of APs affiliated with an AP multilink device (MLD), each of the plurality of APs operating in a corresponding link of the AP MLD, the AP including: circuitry to generate a frame comprising a Traffic Indication Map (TIM) element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffered units of one of a non-AP STA or a non-AP MLD associated with an AP or an AP MLD and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the one of a non-AP STA or a non-AP MLD; and a transmitter which transmits the frame in the link.

Description

Communication device and communication method for multilink traffic indication map

Technical Field

The present embodiments relate generally to communication devices and, more particularly, to methods and apparatus for a multi-link traffic indication map.

Background

In today's world, communication devices are expected to operate wirelessly with the same capabilities as wired computing devices. For example, users desire the ability to seamlessly view high-definition movies streamed to the user's wireless communication device. This presents challenges to the communication device and the access point to which the communication device is wirelessly connected.

The Institute of Electrical and Electronics Engineers (IEEE) 802.11 group has recently established the 802.11 Task Group (TG) to address these challenges. Multilink operation in the 2.4GHz, 5GHz and 6GHz frequency bands has been identified as a candidate technology for such communication. Multi-channel aggregation over multiple links is a natural way to achieve a multiplicative increase in communication data throughput.

In multi-link operation between an Access Point (AP) multi-link device (MLD) and a non-AP MLD, a Traffic Indication Map (TIM) element is carried in a beacon frame, TIM frame, or the like, to indicate buffered traffic (BU) for associated non-AP STAs operating in a Power Save (PS) node. In multi-link operation, in contrast to single-link operation, only the BU indication in the TIM element does not provide additional information about the BU, such as a recommended link to retrieve the BU or a TID associated with the BU. While the method can be used to signal additional information about buffered BUs such as link map, link set indication with link recommendation and TID (traffic identifier), etc., for non-AP MLD to correctly derive (configure out) their position in the link/TID information set, an additional bitmap is needed for each bit set to 1 in the TIM element, regardless of the method used, which will be explained later.

Therefore, there is a need for a communication apparatus and a communication method for a multi-link traffic indication map that solves the above problems and reduces the overhead required to signal additional information about buffered BUs in a WLAN network containing MLD. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

Disclosure of Invention

The non-limiting and exemplary embodiments facilitate providing a communication apparatus and a communication method for a multilink traffic indication map.

In a first embodiment, the present disclosure provides an AP of a plurality of Access Points (APs) affiliated with an (afterfile with) AP multi-link device (MLD), each AP of the plurality of APs operating in a corresponding link of the AP MLD, the AP comprising: circuitry to generate a frame comprising a Traffic Indication Map (TIM) element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for one of a non-AP STA or a non-AP MLD associated with an AP or an AP MLD and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the one of a non-AP STA or a non-AP MLD; and a transmitter which transmits the frame in the link.

In a second embodiment, the present disclosure provides a non-access point (non-AP) multi-link device (MLD) associated with an AP MLD, a non-AP MLD, the non-AP MLD including: a receiver that receives a frame in a link, the frame comprising a Traffic Indication Map (TIM) element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for a non-AP MLD and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the non-AP MLD; circuitry to process a frame.

In a third embodiment, the present disclosure provides a communication method comprising: generating a frame comprising a Traffic Indication Map (TIM) element comprising a virtual bitmap (PVM) partially indicating presence of one or more buffered units for one of a non-AP STA or a non-AP MLD associated with an AP or an AP MLD, and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for one of the non-AP STA or the non-AP MLD; and transmitting the frame in the link.

Other benefits and advantages of the disclosed embodiments will become apparent from the description and drawings. The benefits and/or advantages may be realized by means of the various embodiments and features of the specification and the drawings in isolation, and not all such embodiments and features need be provided to realize one or more of such benefits and/or advantages.

Drawings

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to illustrate various embodiments and to explain various principles and advantages in accordance with the present embodiments.

Fig. 1 depicts a TIM element and a bitmap control field of the TIM element.

Fig. 2 depicts a schematic diagram showing communication between an AP MLD and a non-AP MLD for multi-link power management and traffic indication.

Fig. 3 depicts a set of TIM bit maps and link map bit maps (LMBs).

Fig. 4 depicts a TIM bit map and Link Recommendation (LR) elements.

Fig. 5 depicts a TIM bit map 500 in a TIM element, a Multilink (ML) -TIM element, and an LR element.

Figure 6 depicts a TIM bit map and a Traffic Identifier (TID) bit map.

Figure 7 depicts a TIM bit map and TID indication.

Fig. 8 shows a schematic diagram illustrating an example configuration of a communication device 800 according to the present disclosure.

Fig. 9 depicts a flow diagram illustrating a communication method for a multi-link traffic graph in accordance with various embodiments of the present disclosure.

Fig. 10 depicts an example beacon/TIM frame.

FIG. 11 depicts three example TIM bit maps and example Association Identifier (AID) assignments respectively transmitted by an AP-MLD in three links.

Fig. 12 depicts an example TIM bit map, an example LMB presence bit map, and an example LMB set in a TIM/beacon frame.

Fig. 13 depicts an example TIM bit map, an example LR presence bit map, and an example LR bit map set in a TIM/beacon frame.

Fig. 14 depicts an example TIM bit map, an example link set presence bit map, an example link set bit map, and an example LR bit map set in a TIM/beacon frame.

Figure 15 depicts an example TIM bit map, an example TID information presence bit map, and an example TID information bit map set in a TIM/beacon frame.

Fig. 16 depicts an example TIM bit map, an example AC information present bit map, and an example AC information bit map in a TIM/beacon frame.

FIG. 17 depicts an example AID assignment and three example TIM bit maps transmitted from an AP MLD in three links, respectively.

Fig. 18 depicts an example beacon/TIM frame.

Fig. 19 depicts an example TIM bit map and an example LMB set in a beacon/TIM frame.

Fig. 20 depicts another example beacon/TIM frame.

Figure 21 depicts an example TIM bit map, an example TID information present bit map, and an example TID information bit map set in a beacon/TIM frame.

FIG. 22 depicts an example TIM bit map and an example format of an AC information presence bit map and AC information bit map set transmitted from an AP MLD in a link.

Figure 23 depicts an example format of TIM bit map and TID information present bit map 2304 and TID information bit map in a beacon/TIM frame.

Fig. 24 depicts an example format of a multilink TIM element.

Fig. 25 depicts an example TIM bit map and an example multilink TIM bit map, an example AC information presence bit map, and an example AC information bit map in a beacon/TIM frame.

Fig. 26 depicts an example format of a multilink TIM element including a multilink TIM bit map.

Fig. 27 shows an example configuration of a communication apparatus and two communication devices subordinate to the communication apparatus. According to the present disclosure, the communication device is implemented as an AP MLD and each affiliated communication device may be implemented as an AP configured for a multilink traffic indication map.

Fig. 28 shows an example configuration of a communication apparatus and two communication devices subordinate to the communication apparatus. According to the present disclosure, the communication device is implemented as a non-AP MLD and each affiliated communication device may be implemented as a STA configured for a multilink traffic indication map.

Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures, block diagrams, or flowcharts may be exaggerated relative to other elements to help to improve understanding of the present embodiments.

Detailed Description

The following detailed description is merely exemplary in nature and is not intended to limit the embodiments or the application and uses of the embodiments. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the detailed description. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

In the context of IEEE 802.11 (Wi-Fi) technology, stations (interchangeably referred to as STAs) are communication devices with the capability to use the 802.11 protocol. Based on the IEEE 802.11-2020 definitions, a STA may be any device that contains a Medium Access Control (MAC) compliant with IEEE 802.11 and a physical layer (PHY) interface to the Wireless Medium (WM).

For example, the STA may be a laptop computer, a desktop Personal Computer (PC), a Personal Digital Assistant (PDA), an access point, or a Wi-Fi phone in a Wireless Local Area Network (WLAN) environment. The STAs may be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user device," and "node" are often used interchangeably.

Also, an AP (interchangeably referred to as a Wireless Access Point (WAP) in the context of IEEE 802.11 (Wi-Fi) technology) is a communication device that allows STAs to connect to a wired network in a WLAN. The AP is typically connected to the router (via a wired network) as a stand-alone device, but it may also be integrated with or used in the router.

As described above, a STA may operate as an AP on different occasions in a WLAN, and vice versa. This is because the communication device may include STA hardware components and AP hardware components in the context of IEEE 802.11 (Wi-Fi) technology. In this manner, the communication device may switch between the STA mode and the AP mode based on actual WLAN conditions and/or requirements.

In various embodiments of the present disclosure, a multi-link device (MLD) may refer to a device operating in two or more frequency bands or links (2.4 GHz, 5GHz, or 6 GHz). The MLD may include two or more communication devices corresponding to two or more links, each operating in a particular frequency band or link. For simplicity, each link of the MLD shown in this disclosure is associated with one of many communication devices that are affiliated with the MLD, and the communication apparatus operates mainly in a specific frequency band (2.4 GHz, 5GHz, or 6 GHz) to transmit/receive signals to/from another communication device that is affiliated with the MLD and also operates in the specific frequency band.

In various embodiments of the present disclosure, unless otherwise specified, a non-MLD STA, 11n STA, 11ac STA, or 11ax STA may refer to a legacy (HE/VHT/HT) STA or EHT STA that is not affiliated with the MLD. Similarly, a non-MLD AP may refer to an EHT AP that is not affiliated with an MLD.

In various embodiments of the present disclosure, the partial virtual bitmap (PVM) field refers to a bitmap of a Traffic Indication Map (TIM) element carried in a frame transmitted in a link by an AP or AP MLD, and the terms "PVM" or "partial virtual bitmap" are used interchangeably with TIM bitmap.

A Traffic Indication Map (TIM) element is carried in the beacon frame to indicate buffered traffic (BU) for non-AP STAs operating in a Power Save (PS) mode. Fig. 1 depicts TIM elements and bitmap control fields of TIM element 100. The TIM element 100 includes an element Identifier (ID) field, a length field, a Delivery TIM (DTIM) count field, a DTIM period field, a bitmapA control field 102 and a partial virtual bit map (PVB) field. The bitmap control field 102 includes a traffic indicator field and a bitmap offset field. The length field is set to (N) ₁ +N ₂ ) +4, wherein N ₁ Is the largest even number, such that the traffic indication dummy bit map is numbered 1 through (N) ₁ x 8) -1 bits are all 0, and N ₂ Is the smallest number such that the traffic indication virtual bitmap is numbered (N) ₂ Bits of + 1) × 8 to 2007 are all 0, and when TIM bits at either end of the AID range are all set to 0, N ₁ And N ₂ Is used to signal the actual range of the TIM bit map carried in the PVB field. For an AID, the PVB field is set to 1 to indicate the presence of a buffered BU for the AID. When one or more group addressed Medium Access Control (MAC) service data units (MSDU)/MAC Management Protocol Data Units (MMPDU) are buffered at the AP, the traffic indicator in the TIM element is set to 1 with the DTIM count field set to 0. The DTIM count field is set to the TIM element of 0 when one or more group-addressed MSDUs/MMPDUs are buffered at the AP. The bitmap offset field contains the number N ₁ /2。

For multi-link power management, each STA of a non-AP MLD operating on an enabled link maintains its own power management mode and power state. Each STA of the non-AP MLD can independently change its power management mode or its power state. FIG. 2 depicts a schematic diagram 200 showing communication between an AP MLD 202 and a non-AP MLD 204 for multi-link power management and traffic indication. Frame exchange on an enabled link is possible when STAs (e.g., STA 1, STA 2) of the non-AP MLD 204 operating on the link operate in an active mode or a power-saving mode awake state (e.g., configured with a PM (power management mode) field value of 0); whereas if the AP MLD 202 has buffered traffic (BU) for affiliated STAs (e.g., STA 1, STA 2) of the associated non-AP MLD 204, the affiliated STAs operating in the power saving mode sleep state (e.g., configured with a PM (power management mode) field value of 1), the corresponding affiliated APs (e.g., AP 1, AP 2) on the AP MLD 202 will indicate the buffered traffic of the non-AP MLD 204 using the TIM element carried in the beacon frame.

TID to link mapping is a new mechanism introduced in 802.11be that allows the AP MLD and non-AP MLD that have performed multi-link setup to determine how to map the TID to the setup link in the Downlink (DL) and Uplink (UL). By default, all TIDs map to all established links of UL and DL. If a TID is mapped to a link in a particular direction (DL/UL), transmission of frames belonging to that TID is allowed in that direction.

An established link is defined as enabled if at least one TID is mapped to the link, and as disabled if no TID is mapped to the link. At any point in time, unless admission control is used, the TID will always be mapped to at least one established link. By default, all established links are enabled since all TIDs map to all established links.

If the TID is mapped in the UL to an enabled link set for the non-AP MLD, the non-AP MLD may use any link within the enabled link set to send a frame carrying an MSDU or A-MSDU (aggregated MSDU) having the TID. If the TID is mapped in the DL to an enabled link set for the non-AP MLD, the non-AP MLD may retrieve the buffered BUs corresponding to the TID in any link within the enabled link set, and the AP MLD may use any link within the enabled link set to send frames carrying MSDUs or A-MSDUs having the TID, depending on existing limitations for transmission of frames applicable to those enabled links.

Conventionally, TIM elements are used as they are. For non-AP MLDs, TIM bits are assigned to each non-AP MLD regardless of the number of links established, i.e., a single AID is assigned to the non-AP MLD on all links. The TIM bit for a non-AP STA/MLD is set to 0 if the AP MLD does not have any buffered frames to send to the non-AP STA/MLD, and is set to 1 if the AP MLD has one or more buffered frames to send to the non-AP STA/MLD on any link to use. Any value in the range 1-2007 may be used as the AID for the associated STA according to the IEEE 802.11-2020 specification, however, in various examples used in this disclosure, the AP MLD assigns (allocate) the AID to its associated non-AP STA and non-AP MLD in the AID range 1-255.

Over the conventional TIM element, another element is defined, e.g., an LMB-carrying element, to indicate the buffered data-to-link mapping for each non-AP MLD whose TIM bit is set to 1.

Fig. 3 depicts a TIM bit map 300 and LMB sets 302 in a TIM element. Each bit in the TIM bit map except AID 0 corresponds to the AID of the non-AP STA/MLD. The TIM bit corresponding to AIDs of 12, 28, 35, 57, and 77 is set to 1, indicating that the AP MLD has one or more buffered frames to send to the corresponding STA/MLD associated with the AID. For each bit set to 1 in the TIM bit map 300, there is one LMB. This is for the non-AP MLDs to compute their LMBs' positions in the LMB set 302 based on the bit order set to 1 in the TIM bit map 300. Traditionally, LMBs are required even for legacy STAs to ensure that non-AP MLDs can correctly find their LMBs, since it is not possible to identify legacy STAs based on the TIM bit map 300. In one example, the number of bits in one LMB corresponds to the number of enabled links for non-AP MLD.

The non-AP MLD also checks the LMB corresponding to the AID and identifies the particular link(s) to which buffered traffic is mapped when the non-AP MLD identifies in the TIM element that the TIM bit corresponding to the AID of the non-AP MLD is set to 1. For example, a non-AP MLD with an AID of 28 recognizes its TIM bit set to 1, and therefore the AP MLD has its buffered traffic in one of its enabled links. The non-AP MLD then identifies that its LMB is the second bit in order (the second bit set to 1 in the TIM bit map) and checks the second LMB in LMB set 302. The non-AP MLD then identifies that the second and third bits of its LMB are set to 1, which indicates that the AP MLD has non-AP MLD buffered traffic in link 2 and link 3.

In another conventional example, AIDs are assigned to non-AP MLDs, and the TIM element indicates the BU state for each non-AP MLD. Under the default TID to link mapping, TIDs are mapped to all enabled links. When the bit in the TIM element corresponding to the AID of the non-AP MLD is set to 1, the AP MLD may use the LR element to indicate the recommended link(s), although the non-AP MLD may retrieve buffered data over any of the enabled links. A bitmap in the LR element is assigned to the non-AP MLD, where each bit of the bitmap is mapped to a link and indicates whether use of the link is recommended.

Fig. 4 depicts a TIM bit map 400 and an LR element 402. In the TIM bit map 400, the TIM bits (bits 1 and 3) associated with the AIDs of non-AP MLD1 and non-AP MLD 3 are set to 1, indicating that the AP MLD has one or more buffered frames to send to non-AP MLD1 and non-AP MLD 3. The LR element 402 includes a bitmap for each bit set to 1 in the TIM element 400, in which case the bitmap 1 and the bitmap 3 indicate the recommended links for the non-AP MLD1 and the non-AP MLD 3, respectively. In one example, the number of bits in the LR bitmap corresponds to the number of enabled links for the non-AP MLD. Bit map 1 has values of "1", "0", and "0" indicating that the first link is recommended to the non-AP MLD to retrieve buffered frames from the AP MLD; and the bit map 3 has values of "0", and "1" indicating that a third link is recommended to the non-AP MLD 3 to retrieve buffered frames from the AP MLD.

In addition to the default TID to link mapping, two or more links may be classified under a link set, and different TIDs may also be mapped to different link sets. By using a new multi-link (ML) TIM element, the BU status of different linksets can be indicated. The bitmap in the ML TIM element is assigned to the non-AP MLD. Each bit of the bitmap is mapped to a linkset and indicates the BU state, e.g., set to 1 if there are one or more BUs, and set to 0 if there are no BUs for the linkset. The LR element may also be used to indicate recommended links within a link set.

FIG. 5 depicts a TIM bit map 500, an ML-TIM element 502, and an LR element 504.TID 0-3 is mapped to a first link set comprising link 1 and link 2, while TID 4-7 is mapped to a second link set comprising link 3. The TIM bits (bits 1 and 2) corresponding to the AIDs of non-AP MLD1 and non-AP MLD2 are set to 1, which indicates that the AP MLD has one or more buffered frames to send to non-AP MLD1 and non-AP MLD 2. The ML-TIM element 502 includes a bit map for each bit set to 1 in the TIM element, in which case the bit map 1 and the bit map 2 indicate BU states for different link sets of the non-AP MLD1 and the non-AP MLD2, respectively. The number of bits in the ML-TIM bit map 502 corresponds to the number of link sets. Bit map 1 has values of "1" and "0" indicating that the first link set has a BU for non-AP MLD 1; and bit map 2 has values of "0" and "1," which indicates that the second link set has a BU for non-AP MLD 2.

The LR element 504 also includes a bitmap indicating recommended links within the link set, with bitmap 1 having values of "0" and "1" to indicate recommended links in the second link of link set 1 (i.e., link 2 of non-AP MLD 1). Since bitmap 2 indicates the second link set for non-AP MLD2 and the second link set contains only a single link (link 3), link 3 is recommended for non-AP MLD2 and no separate LR element is needed.

In another conventional example, AIDs are assigned to non-AP MLDs, and the TIM element indicates the BU state for each non-AP MLD. For non-AP MLDs, a TID bit map per bit (8 bits per TID) set to 1 in the TIM element indicates that the AP MLD has TID(s) for one or more BUs of the non-AP MLD. Each bit in the TID bit map represents one TID starting from TID 0, and a bit set to 1 indicates that a buffered frame belonging to the corresponding TID is present at the AP MLD. The STA uses the TID to link mapping to determine which link(s) it should wake up to retrieve buffered MPDUs (MAC protocol data units). In this example, it is assumed that different TIDs are mapped to different links.

Figure 6 depicts a TIM bit map 600 and a TID bit map 602 in a TIM element. In the TIM bit map 600, the TIM bit corresponding to one non-AP STA under AID 27 and five non-AP MLDs under AIDs 12, 28, 35, 57, and 77 is set to 1 to indicate that the AP MLD has one or more buffered frames to transmit to the corresponding STA and MLD, respectively. For each TIM bit for a non-AP MLD set to 1 in the TIM element, there is an 8-bit TID. In this case, the TID bit map 602 includes five 8-bit TIDs for five corresponding non-AP MLDs that have one or more buffered frames to send to. The 8-bit TIDs will be used by the corresponding non-AP MLDs to determine which link(s) they should wake up to retrieve buffered MPDUs from the AP MLDs. However, in this example, it is unclear whether TID indication is also needed for legacy non-AP STAs with AID 27; without it, a non-AP MLD with an AID greater than 27 would not be able to determine the correct TID indication for itself.

Alternatively, the AP signals a single TID using a 3-bit TID bit map 602 instead of 8-bits. Figure 7 depicts a TIM bit map 700 and TID 702 in the TIM element. Signaling a 3-bit TID to each STA/MLD, the AID of each STA/MLD corresponding to the TIM bit set to 1, and if frames belonging to multiple TIDs are buffered at the AP MLD for the non-AP MLD, the signaled TID may be based on certain implementation-specific criteria. The AP delivers an MPDU belonging to the indicated TID on the STA/MLD awake link and carries an A-Control (TID Control) field in the MPDU that signals the AP with an additional TID for the BU of the non-AP MLD. Note the fact that the legacy STA also needs a TID indication in order to enable the non-AP MLD to find the correct TID indication, even if the legacy STA does not know the TID indication.

As previously described, regardless of the method used to signal additional information about buffered BU (e.g., link map, link set indication with link recommendation, and TID indication as shown in fig. 3-7), for each bit set to 1 in the TIM element (including legacy STAs and non-MLD EHT STAs), an additional bit map is needed in order for the non-AP MLDs to correctly derive their position in the link/TID information set. Therefore, there is a need for a communication apparatus and a communication method for a multi-link traffic indication map to solve the above problems and reduce the overhead required to signal additional information on buffered BUs in a WLAN network containing MLD.

According to the present disclosure, two solutions are proposed. Specifically, a presence bitmap is carried in the beacon/TIM/FILS discovery/OPS frame to indicate whether corresponding link/TID/AC information related to the buffered BU of the non-AP STA/MLD is present in the link/TID/AC information set. Even if this bit is set to 0, the presence bitmap can still carry implicit information about the link.

Further, a "start AID" field is carried in the beacon/TIM/FILS discovery/OPS frame to indicate a minimum AID associated with the non-AP MLD for which the link/TID/AC information is included in the link/TID/AC information set (e.g., the AID of the first non-AP MLD). Different portions (e.g., AID space) may be reserved for assigning AIDs to legacy STAs/non-MLD very high throughput (EHT) STAs and to non-AP MLDs to further reduce the overhead of the link/TID/AC information set.

Fig. 8 shows a schematic diagram illustrating an example configuration of a communication device 800 according to the present disclosure. In accordance with the present disclosure, the communications apparatus 800 may be implemented as an AP and a STA and configured for a multi-link traffic indication map. As shown in fig. 8, the communications device 800 may include circuitry 814, at least one radio transmitter 802, at least one radio receiver 804, and at least one antenna 812 (only one antenna is depicted in fig. 8 for simplicity of illustration). Circuitry 814 may include at least one controller 806 for software and hardware assisted execution of tasks that at least one controller 806 is designed to perform, including controlling communication with one or more other communication devices in a multiple-input multiple-output (MIMO) wireless network. The circuitry 814 may also include at least one transmit signal generator 808 and at least one receive signal processor 810. The at least one controller 806 may control at least one transmit signal generator 808 for generating MAC frames (e.g., data frames, management frames, and action frames) to be transmitted by the at least one radio transmitter 802, and at least one receive signal processor 810 for processing MAC frames (e.g., data frames, management frames, and action frames) received by the at least one radio receiver 804 from one or more other communication devices. As shown in fig. 8, the at least one transmit signal generator 808 and the at least one receive signal processor 810 may be separate modules of the communications device 800 that communicate with the at least one controller 806 to implement the functionality described above. Alternatively, the at least one transmit signal generator 808 and the at least one receive signal processor 810 may be included in the at least one controller 806. It is obvious to a person skilled in the art that the arrangement of these functional modules is flexible and may be varied according to actual needs and/or requirements. Data processing, storage and other related control means may be provided on an appropriate circuit board and/or in chipsets. In various embodiments, when operating, the at least one radio transmitter 802, the at least one radio receiver 804, and the at least one antenna 812 may be controlled by the at least one controller 806.

The communications device 800 provides the functionality required for a multilink traffic indication map. For example, communications apparatus 800 may be an AP of a plurality of APs affiliated with an AP MLD, where each AP of the plurality of APs operates in a corresponding link of the AP MLD, and circuitry (e.g., at least one transmit signal generator 808 of circuitry 814) may generate a frame including a Traffic Indication Map (TIM) element including a partial virtual bitmap (PVM) indicating presence of one or more buffer units for one of a non-AP STA or a non-AP MLD associated with the AP or the AP MLD, and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the one of the non-AP STA or the non-AP MLD. The radio transmitter 802 may transmit frames in a link.

For example, the communications apparatus 800 may be a STA of a plurality of STAs affiliated with a non-AP MLD associated with the AP MLD, each STA of the plurality of STAs operating in a corresponding link of the non-AP MLD, and the radio receiver 804 may receive a frame on the link, the frame including a Traffic Indication Map (TIM) element including a partial virtual bitmap (PVM) indicating presence of one or more buffer units for the non-AP MLD and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the non-AP MLD. The circuitry (e.g., the at least one receive signal processor 810 of circuitry 814) may process the frame.

In an embodiment, the frame transmitted/received by the communication apparatus 800 further includes a start Association Identifier (AID) indicating a smallest AID for which additional information related to the one or more BUs exists in the frame. In another embodiment, a first portion of PVMs in the TIM element are associated with AIDs assigned to legacy STAs and non-AP EHT STAs and a second portion of PVMs in the TIM element are associated with AIDs assigned to non-AP MLDs, where the first and second portions of the TIM element do not overlap.

Fig. 9 depicts a flowchart 900 showing a communication method for a multi-link traffic graph according to various embodiments of the present disclosure. In step 902, a step of generating a frame comprising a Traffic Indication Map (TIM) element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for one of a non-AP STA or a non-AP MLD associated with an AP or an AP MLD and a presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the one of a non-AP STA or a non-AP MLD is performed. In step 904, the step of transmitting the frame in the link is performed.

Fig. 10 depicts an example beacon/TIM frame 1000. Although the format of the beacon/TIM frame is shown, it is understood that the same format may be applied to Fast Initial Link Setup (FILS) discovery frames or Operation (OPS) frames. The beacon/TIM frame 1000 carries a TIM element 1002, the TIM element 1002 including a partial virtual bit map (PVM) 1008, a link/TID/AC information presence bit map 1004, a link/TID/AC information set 1006 including link/RID/AC information for each associated MLD. The presence bitmap 1004 indicates whether corresponding link/TID/AC information related to buffered BU for the non-AP MLD is present in the link/TID/AC information set 1004.

The presence bit map 1004 carries 1 bit for each bit set to 1 in the TIM element 1002 in the same order as in PVB 1008. If a corresponding entry of link/TID/AC information exists in the link/TID/AC information set 1006, then the bit in the presence bit map 1004 is set to 1; otherwise it is set to 0.

The bit corresponding to the legacy STA is always set to 0; whereas if for an MLD, link/TID/AC information exists in the link/TID/AC information set 1006, e.g., if the AP MLD has BUs buffered for non-AP MLDs in other links, or if the AP MLD recommends that the non-AP MLD retrieve BUs in another link, or if the AP MLD needs to signal BUs that map to TIDs of other links, the bit corresponding to the MLD is set to 1; and otherwise set to 0, e.g., if the AP MLD has BUs buffered for the non-AP MLD in the same link (referred to herein as the "current link," or may also be referred to as the "transmit link") that transmits the TIM/beacon frame 1000 carrying the TIM element, or if the AP MLD recommends that the non-AP MLD retrieve BUs in the current link, or if all BUs of the non-AP MLD belong to a TID dedicated to mapping to the current link, or for a single link EHT STA or a single link non-AP MLD that listens for beacons on only one link, its bits are set to 0 in all links. Advantageously, the bits set to 0 still carry implicit information about the current link, and the link/TID/AC information is only present for MLDs that need them. With the presence bit map 1004 in the beacon/TIM frame 1000, the non-AP MLD then checks its corresponding bit in the presence bit map 1004 if its corresponding bit in the PVB 1008 is set to 1, and if its bit in the presence bit map 1004 is set to 1, it then further checks the corresponding entry in the link/TID/AC information set 1006 for further information about the BU related to the link/TID/AC.

According to the present disclosure, the same AID is allocated to the MLD on all links, but a unique AID is allocated to the legacy in each link, i.e., the same AID may be allocated to different legacy STAs in different links. Advantageously, there is no restriction on how the AP MLD assigns AIDs.

FIG. 11 depicts three example TIM bit maps 1100, 1110, 1120 and example AID assignments transmitted by an AP-MLD in three links, respectively. MLD1, 2, 3 operating in all three links (link 1, link 2, link 3) and single link MLD 4 are assigned the same AID 12, 28, 57, 77 respectively on the three links; while the legacy STAs are assigned unique AIDs in their respective operating links. Note that the same AID 35 is allocated to different legacy STAs (legacy 1 and legacy 2) in link 1 and link 2, respectively, whereas AID 35 is not allocated in link 3. In the following description in conjunction with fig. 12-16, various embodiments of the present disclosure are based on example AID assignments for the example TIM bit map 1100.

In one embodiment, the presence bitmap 1004 shown in fig. 10 may be a Link Map Bitmap (LMB) and the link/TID/AC information set 1006 shown in fig. 10 is an LMB set, where the presence bitmap indicates whether a corresponding LMB is present in the LMB set. The bit corresponding to the legacy STA is always set to 0; whereas if BU is available only on the link that sent TIM/beacon frames carrying TIM elements, the bit corresponding to MLD is set to 0, e.g., due to TID-to-link mapping or MLD operating only on that link, etc., and is set to 1 if BU is also available on other links. The LMB presence bit map carries bits for each bit set to 1 in the TIM bit map in the same order as in the TIM bit map, and the LMB set carries LMBs for each bit set to 1 in the LMB presence bit map in the same order as in the LMB presence bit map. Advantageously, a bit set to 0 in the LMB presence bit map indicates that the corresponding non-AP MLD only needs to retrieve the BU in the current link and that no LMB is needed in the LMB set, reducing the overhead of link/TID/AC information.

Fig. 12 depicts an example TIM bit map 1200, an example LMB present bit map 1202, and an example LMB set 1204 in a TIM/beacon frame. In the TIM bit map 1200, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 assigned to MLD1, MLD2, legacy 1, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. The LMB presence bit map 1202 carries bits for each bit set to 1 in the TIM bit map 1200 in the same order as in the TIM bit map 1200, so the LMB presence bit map 1202 has a total size of 5 bits.

In this example, the AP MLD transmitting TIM/beacon frames operates in three links (link 1, link 2, and link 3) and shows TIM/beacon frames transmitted in link 1 (referred to herein as the current link). In this example, MLD1 has only BUs mapped to TID of link 1, while MLD 4 operates only on link 1. Since BU for TIDs of MLD1 and MLD 4 is mapped to the current link (link 1), no additional information of MLD1 and MLD 4 is needed, and LMBs in LMB set exist or are needed only for MLD2 and MLD 3. The first and fifth bits in LMB present bit map 1202 corresponding to MLD1 and MLD 4 are set to 0 to indicate that BU is only available on the current link (link 1); and the second and fourth bits in LMB present bit map 1202 corresponding to MLD2 and MLD 3 are set to 1 to indicate that their BU is available on the other link (link 2, link 3). Legacy 1 is a legacy STA, and therefore the third bit in the LMB presence bit map 1202 corresponding to legacy 1 is always set to 0.

LMB set 1204 carries the LMBs for each bit set to 1 in LMB presence bitmap 1202 in the same order as in LMB presence bitmap 1202. In this case, each LMB includes three bits corresponding to three different links (link 1, link 2, link 3), so LMB set 1204 has a total size of 6 bits. The bit in the LMB corresponding to MLD is set to 1 to indicate that BU is available in the corresponding link. In this case, the first LMB in LMB set 1204 that corresponds to MLD2 has the second and third bits set to 1, which indicates that the BU of MLD2 is available in link 2 and link 3. In this example, the total overhead of using the LMB presence bit map 1202 (5 bits) and LMB set 1204 (6 bits) for link/TID/AC information is 11 bits.

In another embodiment, the presence bitmap 1004 may be a Link Recommendation (LR) presence bitmap and the link/TID/AC information sets 1006 are LR bitmap sets. For a default TID to link mapping, where the TID is mapped to all enabled links, the LR presence bitmap indicates whether a corresponding LR bitmap is present in the LR bitmap set. If a link transmitting a TIM/beacon frame carrying a TIM element is recommended, or the AP MLD has no link recommendation, the bit corresponding to the MLD is set to 0; and set to 1 if a link other than the current link is recommended.

The LR presence bitmap carries bits for each bit set to 1 in the TIM bitmap in the same order as in the TIM bitmap, and the LR bitmap set carries the LR bitmap for each bit set to 1 in the LR presence bitmap in the same order as in the LR presence bitmap. Unlike LMBs, the current link is excluded from the LR bitmap because the current link can be recommended by setting the corresponding bit in the LR presence bitmap to 0. Advantageously, a bit set to 0 in the LR presence bitmap indicates that the corresponding non-AP MLD only needs to retrieve the BU in the current link and no LR bitmap is needed in the LR bitmap set, reducing the overhead of link/TID/AC information.

Fig. 13 depicts an example TIM bit map 1300, an example LR present bit map 1302, and an example LR bit map set 1304 in a TIM/beacon frame. In the TIM bit map 1300, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 assigned to MLD1, MLD2, legacy 1, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. The LR presence bit map 1302 carries the bits for each bit set to 1 in the TIM bit map 1300 in the same order as in the TIM bit map 1300, so the LR presence bit map 1302 has a total size of 5 bits.

In this example, the AP MLD transmitting TIM/beacon frames operates in three links (link 1, link 2, and link 3), and TIM/beacon frames are transmitted in link 1 (referred to herein as the current link). MLD1 has only BUs mapped to TID of link 1, while MLD 4 operates only on link 1. Since the BU for the TIDs of MLD1 and MLD 4 are mapped to the current link (link 1), no additional information for MLD1 and MLD 4 is needed, and the LR bit map in LR bit map set 1304 exists or is needed only for MLD2 and MLD 3. The first and fifth bits in LR presence bit map 1302, corresponding to MLD1 and MLD 4, are set to 0, which indicates that BU is only available on the current link (link 1); while the second and fourth bits corresponding to MLD2 and MLD 3 in LR present bit map 1302 are set to 1 to indicate that their BU is also available on the other link (link 2, link 3). Legacy 1 is a legacy STA, and thus the third bit in the LR present bit map 1302 corresponding to legacy 1 is always set to 0.

The LR bitmap set 1304 carries the LR for each bit set to 1 in the LR presence bitmap 1202 in the same order as in the LR presence bitmap 1202. In this case, each LR bitmap includes two bits corresponding to two different links (link 2, link 3) other than the current link (link 1), so the LR bitmap set 1304 has a total size of 4 bits. The bit in the LR bitmap corresponding to the MLD is set to 1 to indicate that BU in links other than the current link is recommended. In this case, the first LR bitmap of LR bitmap set 1304 is associated with MLD2 and its first bit is set to 1, which indicates MLD2 recommended link 2, and the second LR bitmap of LR bitmap set 1304 is associated with MLD 3 and its second bit is set to 1, which indicates MLD 3 recommended link 3. The total overhead of using the link/TID/AC information for LR presence bitmap 1302 (5 bits) and LR set 1304 (4 bits) is 9 bits.

In addition to using LR presence and LR bitmap sets in the default TID to link mapping, when different TIDs are mapped to different link sets, one or more links of enabled links therein may be classified into a link set, which may also be used. In this case, the presence bitmap may be a link set presence bitmap and the link/TID/AC information set is a link set bitmap set. The link set presence bitmap indicates whether a corresponding link set bitmap is present in the link set bitmap set. If the link transmitting the TIM/beacon frame carrying the TIM element is the only link in the link set and only the BU for that link set, the bit corresponding to the MLD is set to 0; and set to 1 if there are BUs for other linksets.

The link set presence bitmap carries bits for each bit set to 1 in the TIM bitmap in the same order as in the TIM bitmap, and the link set bitmap carries the link set bitmap for each bit set to 1 in the link set presence bitmap in the same order as in the link set presence bitmap. The LR bitmap set may also be used for a bit set to 1 in the link set bitmap set to indicate which link in the link set the BU is present on.

FIG. 14 depicts an example TIM bit map 1400, an example linkset presence bit map 1402, an example linkset bit map set 1404, and an LR bit map set 1406. In the TIM bit map 1400, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 assigned to MLD1, MLD2, legacy 1, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. The link set presence bit map 1402 carries the bits for each bit set to 1 in the TIM bit map 1400 in the same order as in the TIM bit map 1400, so the link set presence bit map 1402 has a total size of 5 bits.

In this example, the AP MLD that sends the TIM/beacon frame operates in three links (link 1, link 2, and link 3), and the TIM/beacon frame is sent in link 3 (referred to herein as the current link or current link set). TID 0-3 is mapped to Link 1 and Link 2, so Link 1 and Link 2 can be classified into a Link set (Link set 1), and TID 4-7 is mapped to Link 3, which is classified into another Link set (Link set 2). MLD1 and MLD2 only have BUs mapped to TID of link set 2 (i.e., link 3), while MLD 4 only operates on link 3. Since the BUs for the TIDs of MLD1, MLD2, MLD 4 are mapped to the current link set (link set 2 or link set 3), no additional information for MLD1, MLD2, and MLD 4 is needed, and the link set bitmap in link set bitmap set 1404 exists or is needed only for MLD 3. The first, second, and fifth bits corresponding to MLD1, MLD2, and MLD 4 in link set presence bit map 1402 are set to 0 to indicate that BU is only available on the current link set; and the fourth bit in link set present bit map 1402, corresponding to MLD 3, is set to 1 to indicate that BU is also available on another link set (link set 1). Legacy 1 is a legacy STA, and therefore the third bit in the link set presence bit map 1402 corresponding to legacy 1 is always set to 0.

The link set bitmap set 1404 carries the link set bitmap for each bit set to 1 in the link set presence bitmap 1402 in the same order as in the link set presence bitmap 1402. In this case, each link set bitmap includes two bits corresponding to two different link sets (link set 1, link set 2), so the link set bitmap set 1404 (including only one link set bitmap) has an overall size of 2 bits. The bit in the link set bit map corresponding to the MLD is set to 1 to indicate that the BU is present in the link set. In this case, the first bit of the link set bitmap set associated with MLD 3 is set to 1, which indicates that the BU for MLD 3 is present in link set 1. LR bitmap set 1406 carries an LR bitmap for each bit set to 1 in linkset bitmap set 1404. The bit of the LR bitmap corresponding to a link of a link set indicates that BU is in that link of the link set. In this case, the LR bitmap associated with MLD 3 of LR bitmap set 1406 has its first bit set to 1, which indicates that there is a BU in link 1 of link set 1. The total overhead of using the link set presence bitmap 1402 (5 bits), link set bitmap 1404 (4 bits), and LR bitmap 1406 (2 bits) is 9 bits.

In one embodiment, presence bitmap 1004 as shown in fig. 10 may be a TID information presence bitmap and link/TID/AC information set 1006 is a set of TID information bitmaps, where the LR presence bitmap indicates whether corresponding TID information is present in the set of TID information bitmaps. If the buffered BU belongs only to a TID mapped to the link that sent the TIM/beacon frame carrying the TIM element, the bit corresponding to the MLD is set to 0; and set to 1 if the BU mapped to TIDs of other links are also buffered.

The TID information presence bit map carries bits for each bit set to 1 in the TIM bit map in the same order as in the TIM bit map, and the TID information bit map set carries the TID information bit map for each bit set to 1 in the TID information presence bit map in the same order as in the TID information presence bit map. Advantageously, when the bit for the non-AP MLD in the TID information present bit map is set to 0, the non-AP MLD only needs to retrieve the BU in the current link, while the TID information bit map is not needed in the TID information bit map set, and the overhead of link/TID/AC information is reduced.

Figure 15 depicts an example TIM bit map 1500, TID information present bit map 1502, and TID information bit map set 1506 in a TIM/beacon frame. In the TIM bit map 1500, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 assigned to MLD1, MLD2, legacy 1, MLD 3, and single-link MLD 4, respectively, are set to 1, which indicates that the AP MLD has one or more buffered frames to send to those STAs/MLDs. The TID information presence bit map 1502 carries the bits for each bit set to 1 in the TIM bit map 1500 in the same order as in the TIM bit map, so the TID information presence bit map has a total size of 5 bits.

In this example, the AP MLD that transmits TIM/beacon frames operates in three links (link 1, link 2, and link 3), and TIM/beacon frames are transmitted in link 1 (referred to herein as the current link). MLD1 has only BUs mapped to TID of link 1, while MLD 4 operates only on link 1. Since the BUs for the TIDs of MLD1 and MLD 4 are mapped to the current link, no additional information for MLD1 and MLD 4 is needed, and the TID information bitmap in TID information bitmap set 1504 exists or is needed only for MLD2 and MLD 3. The first and fifth bits corresponding to MLD1 and MLD 4 in TID information presence bit map 1502 are set to 0 to indicate that the buffered BUs for MLD1 and MLD 4 only belong to TIDs mapped into the current link (link 1), while the second and fourth bits corresponding to MLD2 and MLD 3 in TID information presence bit map 1502 are set to 1 to indicate that their BUs mapped to TIDs of the other links (link 2 and link 3) are also buffered. Legacy 1 is a legacy STA, and thus the third bit corresponding to legacy 1 in the TID information present bit map is always set to 0.

The TID information bitmap set 1504 carries TID information bitmaps for each bit set to 1 in the TID information presence bitmap 1502 in the same order as in the TID information presence bitmap 1502. In this case, each TID information bitmap includes eight bits corresponding to eight TIDs (TIDs 0-7), so TID information bitmap set 1504 has a total size of 16 bits. If BUs of TIDs mapped to other links (Link 2, link 3) are also buffered, the bit in the TID information bitmap corresponding to MLD is set to 1. In this case, the TID information bitmap of TID information bitmap set 1504 is associated with MLD2 and its second through seventh bits (corresponding to TID 1-6) are set to 1, which indicates that BUs mapped to TIDs 1-6 of other links are also buffered. In this case, the total overhead of link/TID/AC information using TID information presence bitmap 1502 (5 bits) and TID information bitmap set 1504 (16 bits) is 21 bits.

Alternatively, instead of a TID information bit map (8 bits), a single TID (3 bits) can be signaled in a similar manner as described in fig. 7, but only for the bits of the MLD set to 1 in the TID information presence bit map 1502 (in this case, for MLD2 and MLD 3).

Furthermore, in one embodiment, the TID to link mapping is per Access Category (AC) (per), i.e. two TIDs of an AC are always mapped together to a link and they are never mapped to a link separately. In such embodiments, the presence bitmap may be an AC information presence bitmap and the link/TID/AC information set is an AC information bitmap set, wherein the AC information presence bitmap indicates whether corresponding AC information is present in the AC information bitmap set. If only BUs of TIDs mapped to ACs of links (referred to herein as current links) transmitting TIM/beacon frames carrying TIM elements are buffered, the bit corresponding to MLD is set to 0; and set to 1 if the BU of the TID mapped to the AC of the other link is also buffered. Advantageously, in case the bit for the non-AP MLD in the AC information presence bit map is set to 0, the non-AP MLD only needs to retrieve the BU in the current link.

The AC information presence bitmap carries bits for each bit set to 1 in the TIM bitmap in the same order as in the TIM bitmap, and the set of AC information bitmaps carries the AC information bitmap for each bit set to 1 in the AC information presence bitmap in the same order as in the AC information presence bitmap. Advantageously, the bit for the non-AP MLD in the AC information presence bit map is set to 0, the non-AP MLD only needs to retrieve the BU in the current link, and the AC information bit map is not needed in the AC information bit map set, and the overhead of link/TID/AC information is reduced.

Fig. 16 depicts an example TIM bit map 1600, an example AC information present bit map 1602, and an example AC information bit map set 1604 in a TIM/beacon frame. In the TIM bit map 1600, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 assigned to MLD1, MLD2, legacy 1, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. The AC information presence bit map 1602 carries bits for each bit set to 1 in the TIM bit map 1600 in the same order as in the TIM bit map 1600, so the TID information presence bit map 1602 has a total size of 5 bits.

In this example, the AP MLD transmitting TIM/beacon frames operates in three links (link 1, link 2, and link 3). And TIM/beacon frames are sent in link 1 (referred to herein as the current link). There are four ACs, i.e., AC _ BK, AC _ BE, AC _ VI, and AC _ VO. Two TIDs are mapped to each of the four ACs. An example AC-TID mapping is shown in table 1 below. Two TIDs per AC are always mapped to a link. In this example, AC _ VO and AC _ VI are mapped to link 1 and link 2; and AC _ BE and AC _ BK are mapped to link 3.

MLD1 has only BUs mapped to AC of link 1, while MLD 4 operates only on link 1. Since BUs for the ACs for MLD1 and MLD 4 are mapped to the current link, no additional information for MLD1 and MLD 4 is needed, and the AC information bitmap is only present or needed for MLD2 and MLD 3 in AC information bitmap set 1604. The first and fifth bits corresponding to MLD1 and MLD 4 in the AC information present bit map 1602 are set to 0 to indicate that only BUs mapped to TID of AC of the current link (link 1) is buffered; and the second and fourth bits corresponding to MLD2 and MLD 3 in AC information presence bitmap 1602 are set to 1 to indicate that their BUs mapped to the AC of the other links (link 2 and link 3) are also buffered. Legacy 1 is a legacy STA, and thus the third bit corresponding to legacy 1 in the AC information presence bit map 1602 is always set to 0.

TABLE 1. An example AC-TID mapping

The AC information bitmap set 1604 carries the AC information bitmap for each bit set to 1 in the AC information presence bitmap 1602 in the same order as in the AC information presence bitmap 1602. In this case, each AC information bitmap includes four bits corresponding to four ACs (AC _ BK, AC _ BE, AC _ VI, AC _ VO), and thus the AC information bitmap set 1604 has a total size of 8 bits. In this case, the total overhead of link/TID/AC information using AC information presence bitmap 1602 (5 bits) and AC information bitmap set 1604 (4 bits) is 13 bits.

According to the present disclosure, different portions of the TIM bitmap (e.g., the AID space) may be reserved for assigning AIDs to legacy STAs/non-MLD very high throughput (EHT) STAs and non-AP MLDs, where the different portions do not overlap.

Fig. 17 depicts an example AID assignment and three example TIM bit maps 1700, 1710, 1720 transmitted from an AP MLD in three links, respectively. In this example, the AP MLD uses 255 consecutive AIDs (of the maximum 2007), and the first AID (0) is used to indicate a group-addressed frame and is not assigned to STAs; the latter 30 AIDs (1-30) are reserved for legacy STAs and single link EHT STAs, and the remaining AIDs (31-255) are used for non-AP MLDs.

Each TIM bit is mapped to an AID. Thus, after the first TIM bit associated with AID 0, the latter portion of the TIM bit map (in this case, the portions associated with AIDs 1-30) is reserved for legacy STAs and non-MLD EHT STAs (referred to herein as the AID space for non-MLD STAs), and the remainder of the TIM bit map is used for non-AP MLD (referred to herein as the AID space for non-AP MLD). Advantageously, such AID assignment may also reduce overhead of link/TID/AC information.

As such, with AID assignment, link/AID/AC information related to the buffered BU exists only for the non-AP MLD in the link/AID/AC information set. The starting AID field may be used to indicate that its link/AID/AC information is included in the AID space of the first non-AP MLD in the link/TID/AC information set's non-AP MLD (e.g., the smallest AID). In the following description in conjunction with fig. 19 and 21, various embodiments of the present disclosure are based on example AID assignments for an example TIM bit map 1710.

Fig. 18 depicts an example beacon/TIM frame 1800. Although the format of the beacon/TIM frame is shown, it is understood that the same format may be applied to Fast Initial Link Setup (FILS) discovery frames or Operation (OPS) frames. The beacon/TIM frame 1800 carries a TIM element 1802 including a partial virtual bit map (PVM) 1808, a start AID field 1804, a link/TID/AC information set 1806 including link/RID/AC information for each associated MLD.

Figure 19 depicts a TIM bit map 1900 and an example LMB set 1904 in a beacon/TIM frame. In the TIM bit map 1900, if an AP MLD has one buffered frame to send to a non-AP STA/MLD on any link to be used, the TIM bit is set to 1. The TIM bits corresponding to AIDs 11, 12, 35, 57, 77, 255 assigned to legacy 2, single-link EHT STAs, MLD1, MLD2, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs.

The start AID field 1902 indicates the minimum AID allocated to the non-AP MLD with the TIM bit set to 1, i.e., link/TID/AC information is present in the frame. In this case, the starting AID is 35. By the assignment of non-AP MLD AID spaces and starting AIDs in the TIM bit pattern, the bit pattern may not need to be present, thus reducing the overhead of link/TID/AC information.

Based on the starting AID and TIM bit map 1900 in the starting AID field 1902, the non-AP MLDs can derive the location of their corresponding link/TID/AC information in the link/TID/AC information set. In particular, the starting AID 35 indicates that the first entry in the link/TID/AC information set is associated with the non-AP MLD assigned to the AID 35, which in this case is MLD 1.

Fig. 20 depicts another example beacon/TIM frame 2000. The link/TID/AC information present bitmap 2005 may be used with the start AID field 2004 to further reduce the overhead of link/TID/AC information.

Figure 21 depicts an example TIM bit map 2100, an example TID information present bit map 2104, and an example TID information bit map set 2106 in a beacon/TIM frame. In the TIM bit map 2100, the TIM bits corresponding to AIDs 11, 12, 35, 57, 77, 255 assigned to legacy 2, single-link EHT STAs, MLD1, MLD2, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. In this example, the TIM is transmitted in link 2 and the start AID field 2102 is set to the start of the AID space of the non-AP MLD (AID 31). The TID information present bit map carries bits for corresponding bits set to 1 in the TIM bit map starting from the AID pointed to by the start AID field (i.e., 31). By allocating the non-AP MLD AID space and the start AID 2102 in the TIM bit map 2100, the TID information presence bit map 2104 for the AID spaces (AID 1-30) of the non-MLD STAs is omitted, thus reducing the overhead of link/TID/AC information.

In this example, MLD1 has only BUs mapped to TID of link 2, while MLD 4 operates only on link 1, so TID information for MLD 4 is not included in link 2. No additional information for the buffered BU of MLD1 and MLD 4 is needed and the TID information bit map is only present or needed for MLD2 and MLD 3 in the TID information bit map set 2106. The second and third bits corresponding to MLD2 and MLD 3 in the TID information present bit map 2104 are set to 1 to indicate that their BUs mapped to TIDs of other links are also buffered.

The TID information bitmap set carries the TID information bitmap for each bit set to 1 in the TID information presence bitmap 2104 in the same order as in the TID information presence bitmap 2104. In this case, a single TID (3 bits) is signaled for each of MLD2 and MLD 3, so the TID information bit map set 2106 has a total size of 6 bits. The 3- bit TIDs 101 and 111 signal that the BUs of TIDs 5 and 7 are buffered for MLD2 and MLD 3, respectively. If BUs are present for other TIDs, they are signaled in the A-control field of the subsequent data frames belonging to the indicated TID.

In an embodiment, for APs that are members of a multi-BSSID set (i.e., virtual APs), bits 1 through (2 ^ n-1) of the TIM bit map are used to indicate that one or more group-addressed frames are buffered for each AP (virtual AP) corresponding to a unsent BSSID, and are referred to as a nottxbss identifier (nottxbssid). These bits are not assigned to STAs in the BSS. Furthermore, some AIDs may also be reserved to signal the presence of group-addressed BU to other subordinate APs of the AP MLD, and these AIDs may appear immediately after the AID assigned to the virtual AP, if present. The AP MLD may also reduce the overhead of the legacy STA's link/TID/AC information by properly planning its AID space for the associated non-AP STA/MLD. For example, the AP MLD may assign an AID to the associated non-AP MLD from an AID space starting immediately after the last AID (e.g., 3) reserved for the AP, and assign an AID to the associated non-MLD STA from an AID space starting after the AID space reserved for the non-AP MLD.

Fig. 22 depicts an example TIM bit map 2200 and an example format of an AC information present bit map 2202 and an AC information bit map set 2204 transmitted from an AP MLD in a link. In this example, the AP MLD uses 255 consecutive AIDs (of 2008 maximum), and the first 4 AIDs (0-3) are used to indicate group-addressed frames corresponding to 4 virtual APs; the latter 200 AIDs (4-203) are reserved for non-AP MLDs operating on multiple links, and the remaining AIDs (204-255) are used for legacy STAs and single link EHT STAs.

Each TIM bit is mapped to an AID. Thus, the beginning portion 2211 of the TIM bit map 2202 (in this case, the TIM bits associated with AIDs 0-3) are reserved for the AP MLD (referred to herein as the AID space of the AP MLD). After the AID space 2211 of the AP MLD, the latter portion 2212 of the TIM bit map (in this case, the portions associated with AIDs 11-203) is reserved for the non-AP MLD (referred to herein as the AID space of the non-AP MLD), and the remaining portion 2213 of the TIM bit map is reserved for legacy STAs and non-MLD EHT STAs (referred to herein as the AID space of the non-MLD STAs).

The AID space 2212 for the non-AP MLD starts immediately (appended to the AID space 2211) from the AID space 2211 reserved for the AP in the TIM bit map 2200. A single-link MLD (e.g., single-link MLD 4 in fig. 22) may also be assigned AIDs from the AID space of the non-MLD STAs such that the AID space 2212 of the non-AP MLD is reserved exclusively for non-AP MLDs operating on multiple links. Instead of having a fixed AID space, the AID space boundaries may not be clearly defined. For example, non-AP MLDs operating on multiple links are consecutively assigned AIDs starting with the first available AID (e.g., 4, 5, 6, \8230; etc.), while legacy STAs and single-link EHT STAs are consecutively assigned AIDs starting with the last AID in the AP's AID space backwards (e.g., 255, 254, 253, \8230; etc.). Advantageously, since the AID space reserved for the AP (e.g., non-notxbss ID) is known to all associated STAs, the starting AID is known and may be omitted in this scheme.

Returning to fig. 22, with AID allocation, link/AID/AC information related to buffered BUs exists only for non-AP MLD, whereas legacy STAs and non-MLD EHT STAs are not included in the link/AID/AC information set, so the presence of a bitmap requires only bits for non-AP MLD. The TIM bit corresponding to AIDs 12, 28, 35, 56, 204, 227, 225 assigned to MLD1, MLD2, MLD 3, single link MLD 4, MLD1, MLD2, MLD 3, and single link MLD 4, respectively, is set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. In this example, the TIM is sent in link 3.MLD 1 has only BUs mapped to TID of link 3, while MLD 4 operates only on link 1 and therefore does not include AC information for MLD 4. No additional information for the buffered BU of MLD1 and MLD 4 is needed and the AC information bitmap is only present or needed for MLD2 and MLD 3 in AC information bitmap set 2204. The second and third bits corresponding to MLD2 and MLD 3 in TID information present bit map 2202 are set to 1 to indicate that their BUs mapped to the AC of the other link is also buffered.

The set of AC information bitmaps 2204 carry the AC information bitmap for each bit set to 1 in the AC information presence bitmap 2202 in the same order as in the AC information presence bitmap 2202. In this case, each AC information bitmap includes four bits corresponding to four ACs (AC _ BK, AC _ BE, AC _ VI, AC _ VO), and thus the AC information bitmap set 2204 has a total size of 8 bits. The total overhead of link/TID/AC information using the AC information presence bitmap (3 bits) and the AC information bitmap set (8 bits) is 11 bits.

In another embodiment, even without any restrictions on AID assignment, an indication of the starting AID (e.g., using the starting AID field) may be used to help reduce overhead of link/TID/AC information by excluding STAs whose AIDs are less than the starting AID. The excluded STAs may be legacy STAs, non-MLD EHT STAs or even MLDs where no link/TID/AC information exists.

Fig. 23 depicts an example TIM bit map 2300, an example TID information present bit map 2304, and an example TID information bit map set 2306 in a beacon/TIM frame. The TIM bits corresponding to AIDs 11, 12, 35, 57, 77, 255 assigned to legacy 2, single-link EHT STA, MLD1, legacy 7, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to those STAs/MLDs. Without any limitation on AID assignment, the AID of the legacy STA (e.g., legacy 7) and the AID of the non-AP MLD may be mixed. The start AID field 2302 may indicate the AID of the first non-AP MLD (i.e., the minimum AID associated with the non-AP MLD) for which link/TID/AC information is included in the link/TID/AC information set. In this case, the start AID field 2302 indicates a start AID of 35. This helps to exclude legacy 2 and legacy 3 from the TID information bitmap set. Legacy STAs and non-MLD EHT STAs are still included in the link/TID/AC information set, but only those STAs with AIDs higher than the starting AID (e.g., legacy 7).

The TID information present bit map 2304 carries bits for each bit set to 1 in the TIM bit map in the same order as in TIM bit map 2300, so TID information present bit map 2304 has a total size of 4 bits. In this case, the first and third bits corresponding to MLD1 and MLD 3 in the TID information present bit map 2304 are set to 1.TID information bit map set 2306 carries the TID information bit map for each bit set to 1 in TID information presence bit map 2304 (in this case a single TID with 3 bits) in the same order as in TID information presence bit map 2304. In this case, the first and third bits corresponding to MLD1 and MLD 3 in the TID information present bit map are set to 1, and thus the TID information bit map set 2306 has a size of 6 bits. In this case, the total overhead of link/TID/AC information using the TID information existence bit map 2304 (4 bits) and the TID information bit map set 2306 (6 bits) is 10 bits.

Fig. 24 depicts an example format of a multilink TIM element 2400. The multilink TIM 2400 may be a new element or multilink element with a type field set to "multilink TIM," which is defined to carry a presence bit map and a link/TID/AC information set. The multilink TIM element includes an element field, a length field, an element ID extension field, a multilink control field including a type field (set to "multilink TIM") and a presence bit map, a common information field, and a link information field.

The presence bitmap field of the multi-link control field further includes a start AID presence field and a presence bitmap size presence field, which are used to indicate the presence of the start AID field and the presence bitmap size field in the common information field. The common information field further includes a link/TID/AC information type field, a start AID field, and a presence bitmap size field. The link information field further includes a link/TID/AC information presence bitmap field, a link/TID/AC information presence bitmap, and a link/TID/AC information set field. As shown in table 2 below, the link/TID/AC information type field refers to what type of information is carried in the link/TID/AC information set field. The presence bitmap size field indicates the size of the link/TID/AC information presence bitmap.

The link/TID/AC information present bitmap field indicates whether further information about the buffered BU is present in the link/TID/AC information and is set for non-AP MLD. The link/TID/AC information set field carries further information about the buffered BU for each non-AP MLD.

According to the present disclosure, separate TIM elements (e.g., existing baseline TIM elements) may be used exclusively for signaling buffered BUs for legacy STAs, while new multilink TIM bit patterns are included in the multilink TIM element to signal buffered BUs dedicated to EHT devices, assuming that different AID spaces are reserved for assigning AIDs to legacy STAs (11 n, 11ac, 11ax STAs) and EHT devices (non-MLD EHT non-AP STAs and non-AP MLD). The AID (e.g., AID 0, nottxbss ID, or AID space of AP MLD) for indicating the group address BU is repeated in both the TIM bit map of the legacy STA and the multilink TIM bit map of the EHT device.

TABLE 2 values in the Link/TID/AC information type field and their corresponding information types

Fig. 25 depicts an example TIM bit map 2500 and an example multilink TIM bit map 2510, an example AC information presence bit map, and an example AC information bit map set in a beacon/TIM frame. In this example, the AP MLD uses 1020 consecutive AIDs (out of a maximum of 2008). 510 consecutive AIDs (1-510) are reserved for legacy STAs, and the remaining AIDs (511-1020) are used for EHT devices. Thus, TIM bit map 2500 is used to indicate buffered BUs dedicated to legacy devices, in which case legacy 1 and legacy 2 are assigned under AIDs 34 and 76, respectively, and multilink TIM bit map 2510 is used to indicate buffered BUs dedicated to EHT devices, such as MLD1, MLD2, non-MLD EHT STA 1, MLD 3, and single link MLD 4 assigned under AIDs 51, 528, 535, 557, and 577, respectively. AID for indicating the group address BU, in which case AID 0 is duplicated in the multi-link TIM bit map, as indicated by 2505.

Legacy STAs only need to decode the TIM bit map 2500; while EHT STAs only need to decode the multilink TIM bit map 2510. The bit in the multilink bitmap immediately following the duplicated bit(s) 2505 indicating the group/broadcast addressing frame corresponds to the first AID in the AID space reserved for EHT devices. To avoid bit repetition in the TIM bit map, different AID spaces may be reserved for assigning AIDs to legacy STAs and EHT devices.

As a variation, all non-MLD STAs may also be assigned AIDs from the AID space of the legacy STAs, and the baseline TIM may be used to indicate buffered BUs for the non-MLD STAs. The non-MLD STAs refer to legacy STAs and EHT STAs not affiliated with MLD.

As a further variation, the single-link MLD may also be assigned AIDs from the AID space of the legacy STAs such that the AID space of the legacy STAs is reserved exclusively for the legacy STAs and all EHT devices operating on the single link, and the baseline TIM may also be used to indicate buffered BUs for the single-link MLD. In this case, the multilink TIM bit map is used exclusively to indicate buffered BU only for non-AP MLDs.

AC information presence bit map 2502 carries bits for each bit set to 1 in multilink TIM bit map 2510 in the same order as in multilink TIM bit map 2510, so AC information presence bit map 2502 has a total size of 5 bits. The AC information bitmap set 2504 carries an AC information bitmap for each bit set to 1 in the AC information presence bitmap 2502 in the same order as in the AC information presence bitmap 2502. Each AC information bitmap includes 4 bits corresponding to four ACs. In this case, the first and fourth bits corresponding to MLD2 and MLD 3 in the AC information presence bit map 2502 are set to 1, and thus the AC information bit map set has a size of 8 bits. In this case, the total overhead of link/TID/AC information using a separate TIM element for the EHT device, the AC information presence bit map 2502 (5 bits), and the AC information bit map set 2504 (8 bits) is 13 bits.

Fig. 26 depicts an example format of a multilink TIM element 2600 that includes a multilink TIM bit map. The multilink TIM 2600 includes an element field, a length field, an element ID extension field, a multilink control field including a type field set to "multilink TIM" and a presence bitmap field, a common information field, and a link information field.

The presence bit map field of the multilink control field further includes a start AID presence field, a multilink TIM information presence field, and a presence bit map size presence field, which are used to indicate the presence of the start AID field, the multilink TIM information field, and the presence bit map size field in the common information field. The common information field also includes a link/TID/AC information type field, a start AID field, a multi-link TIM information field, and a presence bit map size field. The link information field further includes a link/TID/AC information presence bitmap field, and a link/TID/AC information set field. The multilink TIM information field also includes a bit map control field, a bit map length field, and a multilink TIM bit map field. The bitmap control field has the same function as the bitmap control field in the conventional TIM element as described and illustrated in fig. 24. The bitmap length field indicates the length of the multilink bitmap in octets (octets). The multilink TIM bit map field indicates a buffered BU dedicated to an EHT device or a non-AP MLD. The link/TID/AC info type field refers to what type of information is carried in the link/TID/AC info set field in a manner similar to that shown in table 2 above. The link/TID/AC information present bitmap field indicates whether further information about the buffered BU is present in the link/TID/AC information and is set for non-AP MLD. The link/TID/AC information set field carries further information about the buffered BU for each non-AP MLD.

Fig. 27 shows an example configuration of a communication apparatus 2700 and three communication devices 2712, 2722, 2732 belonging to the communication apparatus 2700. According to various embodiments in the present disclosure, the communication apparatus 2700 is implemented as an AP MLD, and each of the affiliated communication devices 2712, 2722, 2732 may be implemented as an AP configured for a multilink traffic indication map. The communication device 2700 includes a multi-TIM element generator 2702 that performs a multi-link traffic indication map according to the above embodiments, such as generating a multi-link TIM element including a partial virtual bit map (PVM) indicating the presence of one or more buffer units of an external communication apparatus/device associated with the communication apparatus and a presence bit map with a start AID field, the presence bit map indicating whether additional information related to one or more BUs (e.g., link/TID/AC information) is present on the associated external communication apparatus/device.

The communication device 2700 includes a memory module that stores its MLD MAC MLD address 2701. The communication device 2700 also includes a MAC SAP 2740 for communicating with the internet layer and/or the DS. Each communication apparatus 2712, 2722, 2732 belonging to the communication device provides a link 2718, 2728, 2738 associated with other external communication apparatus/devices and/or DS, and is capable of transmitting (e.g., transmitting a frame including a multi-link TIM element and a presence bitmap having a field related to a start AID) or receiving other signals from the other external communication apparatus/devices and/or DS. Each affiliated communication device 2712, 2722, 2732 comprises a MAC layer 2714, 2724, 2734 and a PHY (physical) layer 2716, 2726, 2736, the PHY layers being connected with a radio transmitter, a radio receiver and an antenna for transmitting/receiving signals to/from other communication devices/apparatuses over the corresponding links 2718, 2728, 2738. In an embodiment, the MAC layer includes a storage module that stores its AP MAC addresses 2715, 2725, 2735 and an optional AP MAC SAP for direct communication with the internet layer for traffic to/from legacy STAs.

Fig. 28 shows an example configuration of a communication apparatus 2800 and three communication devices 2812, 2822, 2832 belonging to the communication apparatus 2800. According to various embodiments in the present disclosure, the communication device 2800 is implemented as a non-AP MLD and each of the affiliated communication apparatuses 2812, 2822, 2832 may be implemented as a STA configured for a multi-link traffic indication map. The communication device 2800 also includes a multi-link TIM element parser 2802 that performs a multi-link traffic indication map according to the embodiments described above, such as receiving and processing a multi-link TIM element including a partial virtual bit map (PVM) indicating the presence of one or more buffer units of the communication device 2700 and a presence bit map with a starting AID field, the presence bit map indicating whether additional information (e.g., link/TID/AC information) related to the one or more BUs is present for the communication device 2800.

The communication device 2800 includes a storage module that stores its MLD MAC MLD address 2801. The communication device 2800 also includes a MAC SAP 2840 for communicating with the internet layer and/or DS. Each of the communications devices 2812, 2822, 2832 affiliated with the communication apparatus provides a link 2818, 2828, 2838 associated with other external communications devices/equipment and/or DSs and is capable of receiving/transmitting other signals therefrom. Each affiliated communication device 2812, 2822, 2832 includes a MAC layer 2814, 2824, 2834 and a PHY (physical) layer 2816, 2826, 2836, the PHY layer being connected with a radio transmitter, a radio receiver and an antenna for transmitting/receiving signals to/from other communication devices/equipment over the corresponding link 2818, 2828, 2838. In an embodiment, the MAC layer includes a storage module that stores its STA MAC addresses 2815, 2825, 2835, and an optional STA MAC SAP for direct communication with the internet layer for traffic to/from legacy APs/STAs.

The present disclosure may be implemented by software, hardware, or a combination of software and hardware. Each of the functional blocks used in the description of each of the embodiments described above may be partially or entirely realized by an LSI such as an integrated circuit, and each of the processes described in each of the embodiments may be partially or entirely controlled by the same LSI or a combination of LSIs. The LSI may be formed solely as a chip, or one chip may be formed to include part or all of the functional blocks. The LSI may include data inputs and outputs coupled thereto. The LSI here may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. However, the technique of implementing an integrated circuit is not limited to the LSI, and may be implemented by using a dedicated circuit, a general-purpose processor, or a dedicated processor. Further, an FPGA (field programmable gate array) which can be programmed after manufacturing an LSI, or a reconfigurable processor in which the connection and setting of circuit cells arranged inside the LSI can be reconfigured may be used. The present disclosure may be implemented as digital processing or analog processing. If future integrated circuit technologies replace LSIs due to advances in semiconductor technology or other derivative technologies, the functional blocks may be integrated using the future integrated circuit technologies. Biotechnology may also be applied.

The present disclosure may be implemented by any kind of apparatus, device or system having a communication function, referred to as a communication apparatus.

Some non-limiting examples of such communication devices include phones (e.g., cellular (cell) phones, smart phones), tablet computers, personal Computers (PCs) (e.g., laptop computers, desktop computers, netbooks), cameras (e.g., digital cameras/camcorders), digital players (digital audio/video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, digital book readers, remote health/telemedicine (remote health and medical) devices, and vehicles that provide communication functionality (e.g., automobiles, airplanes, boats), and various combinations thereof.

The communication devices are not limited to being portable or mobile, but may also include any kind of non-portable or fixed equipment, devices or systems, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other "thing" in an internet of things (IoT) "network.

The communication may include exchanging data via, for example, a cellular system, a wireless LAN system, a satellite system, and the like, as well as various combinations thereof.

The communication device may include a device such as a sensor or controller coupled to the communication device that performs the communication functions described in this disclosure. For example, a communication device may include a controller or sensor that generates control signals or data signals used by the communication device that performs the communication functions of the communication device.

The communication device may also include infrastructure such as base stations, access points, and any other apparatus, device, or system that communicates with or controls devices such as those in the non-limiting examples described above.

A non-limiting example of a station may be a station included in a first plurality of stations affiliated with a multi-link station logical entity (i.e., such as an MLD), where the stations of the first plurality of stations share a common Medium Access Control (MAC) data service interface to an upper layer as part of the first plurality of stations affiliated with the multi-link station logical entity, where the common MAC data service interface is associated with a common MAC address or Traffic Identifier (TID).

It can thus be seen that the present embodiments provide a communication device and method for operating on multiple links in order to fully achieve throughput gains for multi-link communications, particularly for multi-link secure retransmissions.

While exemplary embodiments have been presented in the foregoing detailed description of the present embodiments, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the applicability, operation, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of the operational steps and methods described in an exemplary embodiment and the modules and structures of the device described in an exemplary embodiment without departing from the scope of the subject matter set forth in the appended claims.

Claims (16)

1. An Access Point (AP) affiliated with a plurality of APs of an AP multi-link device (MLD), each AP of the plurality of APs operating in a corresponding link of the AP MLD, the AP comprising:

circuitry to generate a frame comprising a Traffic Indication Map (TIM) element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for one of a non-AP STA or a non-AP MLD associated with the AP or the AP MLD and a presence bitmap indicating whether additional information related to one or more BUs are present in the frame for one of the non-AP STA or the non-AP MLD; and

a transmitter to transmit the frame in a link.

2. The AP of claim 1, wherein the additional information includes at least one of a Link Map Bitmap (LMB), a Link Recommendation (LR), a Link Set Bitmap (LSB), a Traffic Identifier (TID) bitmap, an Access Category (AC) bitmap, a TID, and an AC.

3. The AP of claim 1, wherein the frame further comprises a starting Association Identifier (AID) indicating a smallest AID for which additional information related to one or more BUs is present in the frame.

4. The AP of claim 1, wherein a first portion of PVMs in the TIM element are associated with AIDs allocated to legacy STAs and non-MLD very high throughput (EHT) STAs and a second portion of PVMs in the TIM element are associated with AIDs allocated to non-AP MLDs, wherein the first and second portions of the TIM element do not overlap.

5. The AP of claim 4, wherein the second portion of PVMs in the TIM element associated with the AID assigned to the non-AP MLD begins immediately after the third portion and the first portion of PVMs in the TIM element associated with the AID assigned to the AP.

6. The AP of claim 1, wherein the frame is one of a beacon frame, a TIM frame, a Fast Initial Link Setup (FILS) discovery frame, and an Operations (OPS) frame.

7. The AP of claim 1, wherein PVMs for non-AP MLDs that are subject to MLD and PVMs for non-AP STAs that are subject to MLD are carried in different TIM elements.

8. A non-access point (non-AP) device (MLD) associated with an AP MLD, each STA of the plurality of STAs operating in a corresponding link of the non-AP MLD, the STA comprising:

a receiver to receive a frame in a link, the frame comprising a Traffic Indication Map (TIM) element and a presence bitmap, the elements comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for the non-AP MLD, the presence bitmap indicating whether additional information related to one or more BUs is present in the frame for the non-AP MLD; and

circuitry to process the frame.

9. The STA of claim 8, wherein the additional information includes at least one of a Link Map Bitmap (LMB), a Link Recommendation (LR), a Link Set Bitmap (LSB), a Traffic Identifier (TID) bitmap, an Access Category (AC) bitmap, a TID, and an AC.

10. The STA of claim 8, wherein the presence bitmap indicates that there is no additional information related to one or more BUs for the non-AP MLD, and the STA retrieves the one or more BUs in the link in which the frame was received.

11. The STA of claim 8, wherein the frame is one of a beacon frame, a TIM frame, a Fast Initial Link Setup (FILS) discovery frame, and an Operations (OPS) frame.

12. The STA of claim 8, wherein the frame further comprises a starting Association Identifier (AID) indicating a smallest AID for which additional information related to one or more BUs is first present in the frame.

13. The STA of claim 8, wherein a first portion of PVMs in the TIM element are associated with AIDs allocated to legacy STAs and non-MLD very high throughput (EHT) STAs, and a second portion of PVMs in the TIM element are associated with AIDs allocated to non-AP MLDs, wherein the first and second portions of the TIM element do not overlap.

14. The AP of claim 13, wherein the second portion of PVMs in the TIM element associated with an AID assigned to a non-AP MLD begins immediately after the third portion and the first portion of PVMs in the TIM element associated with an AID assigned to an AP.

15. The AP of claim 8, wherein PVMs for non-AP MLDs that are not affiliated with MLD and PVMs for non-AP STAs that are not affiliated with MLD are carried in different TIM elements.

16. A method of communication, comprising:

generating a frame comprising a Traffic Indication Map (TIM) element and a presence bitmap, the element comprising a partial virtual bitmap (PVM) indicating presence of one or more buffer units for one of a non-AP STA or a non-AP MLD associated with an AP or AP MLD, the presence bitmap indicating whether additional information related to the one or more BUs is present in the frame for the one of the non-AP STA or non-AP MLD; and

the frame is transmitted in the link.

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